// yield/thread/darwin/semaphore.cpp

// Copyright (c) 2011 Minor Gordon
// All rights reserved

// This source file is part of the Yield project.

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution.
// * Neither the name of the Yield project nor the
// names of its contributors may be used to endorse or promote products
// derived from this software without specific prior written permission.

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL Minor Gordon BE LIABLE FOR ANY DIRECT,
// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
// LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
// ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#include "yield/exception.hpp"
#include "yield/time.hpp"
#include "yield/thread/semaphore.hpp"

#include <unistd.h>
#include <mach/clock.h>
#include <mach/mach_init.h>
#include <mach/semaphore.h>
#include <mach/task.h>

namespace yield {
namespace thread {
Semaphore::Semaphore() {
  if (
    semaphore_create(
      mach_task_self(),
      &sem,
      SYNC_POLICY_FIFO,
      0
    ) != KERN_SUCCESS
  )
    throw Exception();
}

Semaphore::~Semaphore() {
  semaphore_destroy(mach_task_self(), sem);
}

void Semaphore::post() {
  semaphore_signal(sem);
}

bool Semaphore::timedwait(const Time& timeout) {
  mach_timespec_t timeout_ts;
  timeout_ts.tv_sec = timeout.ns() / Time::NS_IN_S;
  timeout_ts.tv_nsec = timeout.ns() % Time::NS_IN_S;
  return semaphore_timedwait(sem, timeout_ts) == KERN_SUCCESS;
}

bool Semaphore::trywait() {
  mach_timespec_t timeout_m_ts = { 0, 0 };
  return semaphore_timedwait(sem, timeout_m_ts) == KERN_SUCCESS;
}

bool Semaphore::wait() {
  return semaphore_wait(sem) == KERN_SUCCESS;
}
}
}
